Source for Golden Bean / Hong Kong Kumquat (Fortunella hindsii) seeds?

For the last couple years I have been germinating and growing several kumquat varieties to learn what works for them. My ultimate goal is to use that gained knowledge to successfully grow some of this particular variety.

For the last couple years I have searched online for a reputable source of seeds to no avail. One European supplier is "out of stock", and has been so for quite a while. An Amazon vendor offers them regularly, but doesn't have a good reputation, as the seeds that have been delivered "do not appear to be those of Fortunella hindsii.

I feel I have exhausted my resources, so I am hoping to find assistance in this much larger knowledge base. Any links or hints would be greatly appreciated!

That's one of those words that sound dirty buy really isn't. Like moist.
Kumquat.
Just rolls off the tongue.